Method of manufacturing a circuit device

ABSTRACT

In one form, a method of manufacturing a circuit device comprises providing a lead frame comprising a plurality of leads, each comprising an island portion, a bonding portion elevated from the island portion, a slope portion extending obliquely so as to connect the island portion and the bonding portion, and a lead portion extending from the bonding portion. The circuit elements are mounted on upper surfaces of the island portions, and are connected to corresponding bonding portions by wirings. Two leads are adapted to be connected to positive and negative sides of a power source, and another lead is an output lead for providing alternating-current power. Lower surfaces of the island portions are attached to an upper surface of a circuit board. The circuit board, the circuit elements, and the lead frame are encapsulated by a resin, so that the lead portions are not covered by the resin.

This application is a division of U.S. patent application Ser. No.13/242,202, filed Sep. 23, 2011, entitled “Circuit Device and Method ofManufacturing the Same,” and claims priority from Japanese PatentApplication Number JP 2010-213694 filed on Sep. 24, 2010, the content ofwhich is incorporated herein by reference in its entirety.

BACKGROUND

1. Field

The invention relates to a circuit device and a method of manufacturingthe same, and more particularly relates to a circuit deviceincorporating a power semiconductor element that performs switching of alarge current and to a method of manufacturing the same.

2. Description of the Related Art

A structure of a conventional hybrid integrated circuit device 100 isdescribed with reference to FIG. 9. This technology is described forinstance in Japanese Patent Application Publication No. Hei 5-102645. Aconductive pattern 103 is formed on a surface of a rectangular substrate101 with an insulative layer 102 interposed therebetween. A certainelectrical circuit is formed by fixedly attaching circuit elements onthe conductive pattern 103. Here, a semiconductor element 105A and achip element 105B as the circuit elements are connected to theconductive pattern 103. Leads 104 are connected to pads 109 each formedof a part of the conductive pattern 103 at a peripheral portion of thesubstrate 101 and function as external terminals. An encapsulating resin108 has a function of encapsulating the electrical circuit formed on thesurface of the substrate 101.

The semiconductor element 105A is a power element through which a largecurrent of about several to several hundreds of amperes flows forexample and thus generates an extremely large amount of heat. Thus, thesemiconductor element 105A has been placed on an upper portion of a heatsink 110 placed on the conductive pattern 103. The heat sink 110 is madeof a piece of metal such as copper having a size of aboutlength×width×thickness=10 mm×10 mm×1 mm for example.

However, in the hybrid integrated circuit device 100 having thestructure, to form a circuit such as an inverter circuit for convertinga large current on the upper surface of the substrate 101, theconductive pattern 103 needs to be wide to secure a current capacity.Thus, downsizing of the hybrid integrated circuit device 100 ishindered. Moreover, a heat sink needs to be prepared for eachsemiconductor element to secure heat dissipation, whereby the cost isincreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view and FIG. 1B is a cross-sectional viewshowing a circuit device according to a preferred embodiment of theinvention.

FIG. 2 is a plan view of the circuit device according to the preferredembodiment of the invention.

FIGS. 3A and 3B are cross-sectional views partially showing the circuitdevice according to the preferred embodiment of the invention.

FIG. 4A is a circuit diagram of an inverter circuit to be incorporated.FIG. 4B is an extracted plan view of the leads. FIG. 4C is across-sectional view showing the lead.

FIG. 5 is a cross-sectional view of a circuit device according toanother preferred embodiment of the invention.

FIG. 6A is a plan view and FIG. 6B is a cross-sectional view showing amethod of manufacturing the circuit device according to the preferredembodiment of the invention.

FIG. 7A is a plan view and FIG. 7B is a cross-sectional view showing themethod of manufacturing the circuit device according to the preferredembodiment of the invention.

FIG. 8A is a plan view and FIG. 8B is a cross-sectional view showing themethod of manufacturing the circuit device according to the preferredembodiment of the invention.

FIG. 9 is a cross-sectional view of a hybrid integrated circuit devicedescribed in Description of the Related Art.

The use of the same reference symbols in different drawings indicatessimilar or identical items.

DETAILED DESCRIPTION

First of all, a structure of a hybrid integrated circuit device 10 as anexample of a circuit device is described with reference to FIGS. 1Athrough 5.

The structure of the hybrid integrated circuit device 10 according tothis embodiment is described with reference to FIGS. 1A and 1B. FIG. 1Ais a perspective view showing the hybrid integrated circuit device 10 asviewed from an obliquely upper direction. FIG. 1B is a cross-sectionalview of the hybrid integrated circuit device 10.

Referring to FIGS. 1A and 1B, the hybrid integrated circuit device 10includes a circuit board 12, leads 18 and 20 disposed on the uppersurface of the circuit board 12, a transistor 22 and a diode 24 (circuitelements) disposed on an island portion 28 of the lead 18, and anencapsulating resin 16 integrally covering the components.

The circuit board 12 is a metal substrate mainly made of metal such asaluminum (Al) or copper (Cu). Specifically, the circuit board 12 has asize of about length×width×thickness=30 mm×15 mm×1.5 mm for example.When a substrate made of aluminum is used as the circuit board 12, bothmain surfaces of the circuit board 12 are subjected to alumitetreatment. Here, the upper and the side surfaces of the circuit board 12are covered with the encapsulating resin 16 and the lower surface isexposed to the outside. Thus, a heat sink can be brought into contactwith the exposed lower surface of the circuit board 12, whereby the heatdissipation is improved. Alternatively, the lower surface of the circuitboard 12 may be covered with the encapsulating resin 16 to securemoisture resistance and withstand voltage.

Referring to FIG. 1B, the leads 18 and 20 are respectively provided onthe left and the right sides in the drawing. Here, a large number ofleads 18 and 20 are disposed along two opposite sides of the circuitboard 12. Instead, only the leads 18 may be disposed along one side, orthe leads may be disposed along four sides.

A plurality of the leads 18 are provided along one side of the circuitboard 12. The lead 18 includes the island portion 28, a slope portion30, a bonding portion 34, and a lead portion 32 in this order from theinner side. The transistor 22 and a diode 24 are fixedly attached on theupper surface of the island portion 28 with a conductive adhesive suchas solder. The lower surface of the island portion 28 is fixedlyattached on the upper surface of the circuit board 12. Thus, the heatgenerated by the transistor 22 and the diode 24 during operation isfavorably radiated outside through the island portion 28 and the circuitboard 12. Providing the slope portion 30 in an intermediate portion ofthe lead 18 separates the left upper end of the circuit board 12 fromthe lead 18 and thus prevents short circuiting of the circuit board 12and the lead 18. The bonding portion 34 is a portion connected to thetransistor 22 and the diode 24 through a fine metal wire 26 (an aluminumwire having a diameter in a range from 20 μm to 500 μm, for example). Aconnection structure through the metal wire 26 is described later withreference to FIG. 4B. The lead portion 32 is a terminal portion that isled out from the encapsulating resin 16 to be used for insert mountingand the like.

A plurality of the leads 20 are provided at positions opposite to thoseof the leads 18. The lead 20 includes a bonding portion 36, a slopeportion 39, and a lead portion 38 in this order from the inner side. Thebonding portion 36 is fixedly attached on the upper surface of thecircuit board 12 and is electrically connected to a control electrode ofthe transistor 22 mounted on the island portion 28. The lead portion 38is led out from the encapsulating resin 16 through the slope portion 39.

The leads 18 and the leads 20 have different functions. Specifically, onthe leads 18, the transistors 22 and the diodes 24 are mounted to forman inverter circuit. Thus, the leads 18 also serve as paths throughwhich direct-current power to be converted by the inverter circuit andalternate-current power obtained by the conversion pass. Moreover, theleads 18 are each formed of a thick piece of metal such as copper havinga thickness of about 500 μm and thus also functions as a heat sink.Meanwhile, the lead 20 is connected to the control electrode of thetransistor 22 and thus serves as a connection terminal through which acontrol signal passes.

Here, the transistor 22 and the like are connected through one finemetal wire 26 in the figure. Instead, the electrical connection of thetransistor 22 may be achieved through multiple (two or three forexample) fine metal wires 26. As connecting means connecting thetransistor 22 and the like, a metal foil formed by ribbon bonding may beemployed in place of the fine metal wire.

Structures of the leads 18 and 20 are described with reference to FIG.2. Referring to the figure, leads 18A to 18H and leads 20A to 20H aredisposed opposite to each other.

Of the leads 18A to 18H, the leads 18A and 18H respectively disposed onthe left and the right ends are leads through which a direct current issupplied from the outside, and the leads 18 c, 18D and 18E are leadsthrough which alternate-current power of three phases obtained by theconversion in the incorporated inverter circuit is outputted. A resistor45 for detecting a current value is disposed between the leads 18A and18B.

On the upper surfaces of the leads 18C to 18E, the transistors and thediodes that form the three phase inverter circuit are mounted. This isdescribed in detail later with reference to FIG. 4.

Of the leads 20A to 20H, the leads 20A and 20B are respectivelyconnected to the leads 18A and 18B through the fine metal wires 26 andare used for detecting the current value. The leads 20C to 20H areconnected to the control electrodes of the transistors mounted on theleads 18C to 18H. Specifically, when the transistor is an IGBT, theleads 18C to 18H are connected to gate electrodes of the IGBTs.

Structures in which the island portion 28 of the lead is fixedlyattached on the upper surface of the circuit board 12 is described withreference to cross-sectional views of FIG. 3A and FIG. 3B.

Referring to FIG. 3A, the upper surface of the circuit board 12 made ofmetal such as aluminum is covered with an insulative layer 44. Theinsulative layer 44 is made of epoxy resin or the like highly filledwith filler such as AL₂O₃ in an amount of about 60% by weight to 80% byweight, for example. A conductive pattern 46 made of metal such ascopper and having a thickness of about 50 μm is formed on the uppersurface of the insulative layer 44. The island portion 28 of the lead isfixedly attached on the upper surface of the conductive pattern 46 withan adhesive 48 such as solder provided therebetween. Thus, the heatgenerated by the transistor 22 during operation is radiated outsidethrough the island portion 28, the adhesive 48, the conductive pattern46, and the circuit board 12.

In FIG. 3B no conductive pattern is formed on the upper surface of theinsulative layer 44. The lower surface of the island portion 28 isfixedly attached on the upper surface of the insulative layer 44 withthe conductive or insulative adhesive 48 provided therebetween.

The bonding portion 36 of the lead 20 shown in FIG. 1B is fixedlyattached on the upper surface of the circuit board 12 in a structuresimilar to that described above.

Referring to FIGS. 4A, 4B, and 4C, a structure in a case where the threephase inverter circuit is incorporated in the hybrid integrated circuitdevice 10 is described. FIG. 4A is a circuit diagram of the invertercircuit, FIG. 4B is a plan view showing a configuration of the leads,and FIG. 4C is a cross-sectional view of the lead 18.

Referring to FIG. 4A, the inverter circuit 56 includes six IGBTs (Q1 toQ6) and six diodes (D1 to D6). The IGBTs Q1 to Q3 are high sidetransistors while the IGBTs Q4 to Q6 are low side transistors. Theflywheel diodes (D1 to D6) are connected to the collector electrode andthe emitter electrode of the respective IGBTs (Q1 to Q6) in inverseparallel. By thus connecting the flywheel diodes with the IGBTs ininverse parallel, the IGBTs are prevented from being broken by an overvoltage due to counter electromotive force generated in an inductiveload. Here, other transistors such as a MOS and like may be used inplace of the IGBT.

The IGBTs (Q1) and (Q4) are serially connected and exclusively ON/OFFcontrolled. The alternate-current power of U phase is outputted to theoutside from the midpoint of the IGBTs (Q1) and (Q4) through the lead.The IGBTs (Q2) and (Q5) are serially connected and the alternate-currentpower of V phase is outputted to the outside from the midpoint of theIGBTs (Q2) and (Q5) that are exclusively ON/OFF controlled. The IGBTs(Q3) and (Q6) are serially connected and the alternate-current power ofW phase is outputted to the outside from the midpoint of the IGBTs (Q3)and (Q6) that are exclusively ON/OFF controlled. Switching of the IGBTsis controlled by the control element positioned outside the device.

With this structure, the inverter circuit 56 converts receiveddirect-current power into alternate-current power of three phases (U, V,W) which rotationally drives a motor M as a load.

Referring to FIG. 4B, the IGBTs and the diodes are fixedly attached onthe upper surfaces of the island portions 28C to 28H of the leads 18C to18H with a conductive adhesive such as solder. Specifically, the IGBT(Q1) and the diode D1 are mounted on the island portion 28C of the lead18C, while the IGBT (Q2) and the diode D2 are mounted on the islandportion 28D of the lead 18D. The IGBT (Q3) and the diode D3 are mountedon the island portion 28E of the lead 18E, while three IGBTs (Q4 to Q6)and three diodes D4 to D6 are mounted on the island portion 28H of thelead 18H. A collector electrode formed on the back surface of each IGBTand a cathode electrode of each diode are connected to the upper surfaceof a corresponding island portion with a conductive adhesive such assolder.

The transistors and the diodes mounted on the island portions areconnected with each other through the fine metal wires to form theinverter circuit. In this embodiment, the transistor and the diodemounted on each island are connected with a bonding portion of anadjacent lead through a fine metal wire.

Specifically, the IGBT (Q1) and the diode D1 mounted on the islandportion 28C of the lead 18C respectively have an emitter electrode andan anode electrode connected to a bonding portion 34B of the lead 18Bthrough the fine metal wire 26. The IGBT (Q2) and the diode D2 mountedon the island portion 28D of the lead 18D respectively have an emitterelectrode and an anode electrode connected to a bonding portion 34C ofthe lead 18C through the fine metal wire 26. The IGBT (Q3) and the diodeD3 mounted on the island portion 28E of the lead 18E respectively havean emitter electrode and an anode electrode connected to a bondingportion 34D of the lead 18D through the fine metal wire 26.

Moreover, the IGBTs (Q4 to Q6) and the diodes D4 to D6 mounted on theisland portion 28H connected to the negative side of a direct-currentpower source are connected to the respective bonding portions 34C to 34Eof the leads 18D to 18F. Specifically, an emitter electrode of the IGBT(Q4) and an anode electrode of the diode D4 are connected to the bondingportion 34C of the lead 18C through the fine metal wire 26. An emitterelectrode of the IGBT (Q5) and an anode electrode of the diode D5 areconnected to the bonding portion 34D of the lead 18D through the finemetal wire 26. An emitter electrode of the IGBT (Q6) and an anodeelectrode of the diode D6 are connected to the bonding portion 34E ofthe lead 18E through the fine metal wire 26.

In this embodiment, the adjacent leads are connected with each otherthrough the fine metal wires. The fine metal wire 26 connecting the IGBT(Q4) and the diode D4 with the bonding portion 34C of the lead 18C isformed to pass above the leads 18D and 18E. If the leads 18B to 18H areentirely flat, the fine metal wires 26 formed in such a complex mannermay contact with each other and cause short circuiting. In thisembodiment, the bonding portion 34 to which the fine metal wire isconnected is positioned above the island portion 28 with the slopeportion 30 provided therebetween as shown in FIG. 4C. Thus, the finemetal wires formed in a complex manner to form the inverter circuit areprevented from being in contact and causing short circuiting.

Furthermore, in this embodiment, no conductive pattern is formed on theupper surface of the circuit board 12 and the transistor 22 and thediode 24 are mounted on the island portion 28 of the lead 18 placed onthe upper surface of the circuit board 12 as shown in FIG. 1B. Thus, theleads 18 of the present embodiment not only serve as external outputterminals but also serve as the conductive pattern in Description of theRelated Art. The island portion 28 of the lead 18 has a thickness ofabout 500 μm, for example, and thus is formed to have a thickness largerthan that (50 μm) of the conductive pattern formed on the upper surfaceof the circuit board described in Description of the Related Art. Thethin conductive pattern is formed over a wide area to deal with a largecurrent of about several tens of amperes in the conventional case. Inthe present embodiment however, the lead 18 is thick and thus has alarge cross-sectional area. Thus the area occupied by the lead 18 can bemade smaller compared with the conventional conductive pattern. Thiscontributes to the downsizing of the device as a whole.

A structure of a hybrid integrated circuit device 10A of anotherpreferred embodiment is described with reference to FIG. 5. A basicstructure of the hybrid integrated circuit device 10A shown in thisfigure is same as that of the device shown in FIG. 1. The differencefrom the structure in FIG. 1 is that a control board 14 is fixedlyattached on the upper surface of the circuit board 12.

Specifically, the island portion 28 of the lead 18 is fixedly attachedon left side in the drawing of the upper surface of the circuit board 12as in the structure described above.

The control board 14 having a control element 42 mounted on its uppersurface is fixedly attached on the right side in the drawing of theupper surface of the circuit board. The control board 14 is formed of aninexpensive insulative substrate such as a glass epoxy substrate. Aconductive pattern is formed on the upper surface of the control board14. The control element 42 in a form of a resin encapsulated package isconnected to the conductive pattern. The control element 42 is connectedto the control electrode of the transistor 22 through the conductivepattern formed on the upper surface of the control board 14 and the finemetal wire. Thus, the transistor 22 in the inverter circuit iscontrolled by a control signal supplied from the control element 42. Thecontrol element 42 is connected to the lead 20 on the right side of thedrawing through the conductive pattern on the control board 14 and thefine metal wire 26.

By providing the control element 42 in the hybrid integrated circuitdevice 10A, a module in which the inverter circuit and the controlcircuit are integrated is formed, whereby the device as a whole can havea high performance. Moreover, the control element 42 is mounted on thecontrol board 14 placed on the upper surface of the circuit board 12made of a metal material, whereby the control element 42 is preventedfrom being over heated. Specifically, even when the heat generated bythe transistor 22 during operation is transmitted to the circuit board12 made of metal, the transmission of the heat to the control element 42is prevented by the control board 14 made of an insulative material suchas a resin material.

The control element 42 may be mounted on the conductive pattern formeddirectly on the upper surface of the circuit board 12 without disposingthe control board 14 on the upper surface of the circuit board 12.

Next, a method of manufacturing the hybrid integrated circuit device 10having the above described structure is described with reference to FIG.6 to FIG. 8.

Referring to FIGS. 6A and 6B, first of all, a lead frame 58 includingmultiple leads 18 and 20 are prepared. FIG. 6A is a plan view showingone unit 60 to be provided in the lead frame 58. FIG. 6B is across-sectional view of the unit 60.

Referring to FIG. 6A, the unit 60 includes a large number of leads 18and 20 forming a single hybrid integrated circuit device. Each of theleads 18 and 20 has one end positioned in an area on which the circuitboard 12 is to be placed. The leads 18 are disposed on the left side ofthe unit 60 in the drawing and are provided with the island portions 28on which the transistors and the diodes are mounted as described above.The leads 20 are disposed on the right side in the drawing and serve asexternal connection terminals and also are responsible for theconnection of the control electrode of the transistor and mechanicallysupporting the control board. An outer end of each of the leads 18 and20 is integrally supported by a tie bar 62 continuous with an outerframe 64.

As shown in FIG. 6B, the lead 18 on the left side in the drawingincludes the island portion 28, the slope portion 30, the bondingportion 34, and the lead portion 32. Here, the island portion 28 is aportion on which a circuit element such as the transistor is mounted.The bonding portion 34 is a portion to which the fine metal wire isconnected. The lead 20 on the right side of the drawing includes thebonding portion 36, the slope portion 39, and the lead portion 38.

The lead frame 58 includes a plurality of the units 60 having thestructure within the frame-shaped outer frame 64. The following stepsare collectively performed on the units 60.

Referring to FIGS. 7A and 7B, the circuit elements and the circuit boardare fixedly attached on the leads. FIG. 7A is a plan view showing thepresent step and FIG. 7B is a cross-sectional view.

Specifically, the back surface electrode of the transistor 22 is fixedlyattached on the island portion 28 of the lead 18 with a conductiveadhesive such as solder. The back surface electrode of the diode 24 isfixedly attached in a similar manner. Then, the electrode of thetransistor 22 is connected to the bonding portion 34 provided at theintermediate portion of the lead 18 through the fine metal wire 26.Similarly, the control electrode (gate electrode) of the transistor 22is connected to the bonding portion 36 of the lead 20 through the finemetal wire 26.

Referring to FIG. 7B, the island portion 28 of the lead 18 is fixedlyattached on the upper surface of the circuit board 12. The lower surfaceof the island portion 28 may be fixedly attached on the upper surface ofthe circuit board 12 as follows. Specifically, the island portion 28 maybe fixedly attached on the conductive pattern 46 formed on the uppersurface of the circuit board 12 as shown in FIG. 3A or may be directlyfixedly attached on the upper surface of the insulative layer 44covering the upper surface of the circuit board 12 as shown in FIG. 3B.

In this step, the transistors 22 and the diodes 24 mounted on the islandportions 28 of the leads 18 are connected to the bonding portions 34through the fine metal wires 26 so that the inverter circuit is formedin each unit 60. The connection structure using the fine metal wires 26is as described with reference to FIG. 4. In this embodiment, the finemetal wires 26 are formed in a complex manner to form the invertercircuit. Accordingly, when the leads 18 have a flat shape, the finemetal wires 26 may be in contact with each other and cause shortcircuiting. In this embodiment, the bonding portion 34 to which the finemetal wire 26 is connected is disposed at a higher position than theisland portion 28 so that the fine metal wires 26 are separated from oneanother to prevent short circuiting.

Here, to manufacture the hybrid integrated circuit device 10A shown inFIG. 5, the control board 14 on which the control element 42 is mountedis disposed on the upper surface of the circuit board 12 and the controlboard 14, the transistor 22, and the lead 20 are connected to each otherthrough the fine metal wires 26.

Referring to FIGS. 8A and 8B, next, an encapsulating resin is formed tocover the circuit board 12. FIG. 8A is a cross-sectional view showingthe step of molding the circuit board 12 using a mold and FIG. 8B is aplan view showing the lead frame 58 after the molding.

Referring to FIG. 8A, the circuit board 12 fixed to the lead frame isplaced in a cavity 72 defined by an upper mold 68 and a lower mold 70.Here, the position of the circuit board 12 in the cavity 72 is fixed byclamping the leads 18 and 20 with the upper mold 68 and the lower mold70. Then, the circuit board 12 and the circuit elements and the like areencapsulated by injecting resin into the cavity 72 through a gateprovided to the mold. In this step, transfer molding using athermosetting resin or injection molding using a thermoplastic resin isperformed. The encapsulating structure of the circuit board 12 is notlimited to the resin encapsulation and an encapsulation by potting or anencapsulation using a case member may also be employed.

Referring to FIG. 8B, after the molding step is completed, the leads 18and 20 are separated from the lead frame 58 by press work. Specifically,the leads 18 and 20 are individually separated at a portion at which thetie bar 62 is provided. Thus, the hybrid integrated circuit device asshown in FIG. 1 is separated from the lead frame 58.

According to the present invention, the lead is provided with the islandportion and the bonding portion that are continuous through the slopeportion. The island portion is fixedly attached on the upper surface ofthe circuit board while the bonding portion is disposed at a higherposition than the upper surface of the circuit board to be separatedtherefrom. The circuit element mounted on the island portion and thebonding portion are connected with each other through connecting means.Thus, the connecting means made of a fine metal wire, for example, isprevented from contacting another connecting means and thus the shortcircuiting is prevented. Thus, a relatively complex circuit such as aninverter circuit can be formed with a plurality of leads and connectingmeans.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments that fall within thetrue scope of the claims. Thus, to the maximum extent allowed by law,the scope of the present invention is to be determined by the broadestpermissible interpretation of the following claims and theirequivalents, and shall not be restricted or limited by the foregoingdetailed description.

What is claimed is:
 1. A method of manufacturing a circuit device,comprising: providing a lead frame comprising a plurality of leads, eachof the leads comprising an island portion, a bonding portion elevatedfrom the island portion, a slope portion extending obliquely so as toconnect the island portion and the bonding portion, and a lead portionextending from the bonding portion, mounting circuit elements on uppersurfaces of the island portions; connecting the circuit elements tocorresponding bonding portions by wirings wherein one of the pluralityof leads is a first input lead adapted to be connected to a positiveelectrode side of a direct-current power source, another of theplurality of leads is a second input lead adapted to be connected to anegative electrode side of the direct-current power source, and yetanother of the plurality of leads is an output lead through whichalternating-current power obtained by converting direct-current powerinputted through the first input lead and the second input lead isadapted to be outputted; attaching lower surfaces of the island portionsto an upper surface of a circuit board; and encapsulating by a resin thecircuit board, the circuit elements and the lead frame so that the leadportions are not covered by the resin.
 2. The method of claim 1, whereina circuit element mounted on an island portion of one of the leads and abonding portion of another of the leads are electrically connectedthrough a wiring.
 3. The method of claim 2, wherein there is no otherlead between the one of the leads and the other of the leads.
 4. Themethod of claim 2, wherein there is at least one lead between the one ofthe leads and the other of the leads, and the wiring passes above the atleast one lead.
 5. The method of claim 1, wherein mounting circuitelements on upper surfaces of the island portions comprises: mounting adiode on an upper surface of the island portion of a first lead; andmounting a transistor on the upper surface of the island portion of thefirst lead.
 6. The method of claim 5, wherein mounting the transistor onthe upper surface of the island portion of the first lead furthercomprises: mounting an insulated gate bipolar transistor on the uppersurface of the island portion of the first lead.
 7. The method of claim6, further comprising: mounting an insulative control board on the uppersurface of the circuit board; and mounting a control element on an uppersurface of the insulative control board.
 8. The method of claim 7,further comprising: connecting the control element to at least one ofthe circuit elements through at least one wiring
 9. The method of claim8, wherein connecting the control element to the at least one of thecircuit elements through the at least one wiring comprises: connectingthe control element to the transistor through the at least one wiring.10. The method of claim 1, further comprising: mounting an insulativecontrol board on the upper surface of the circuit board; and mounting acontrol element on an upper surface of the insulative control board. 11.The method of claim 10, further comprising: connecting the controlelement to at least one of the circuit elements through at least onewiring
 12. A method of manufacturing a circuit device, comprising:providing a lead frame comprising a plurality of leads, each comprisingan island portion, a bonding portion elevated from the island portion, aslope portion extending obliquely so as to connect the island portionand the bonding portion, and a lead portion extending from the bondingportion, mounting a first transistor and a first diode of a first phaseon an upper surface of the island portion of a first lead; connectingthe first transistor and the first diode of the first phase to a bondingportion of a second lead by a first wiring; mounting a second transistorand a second diode of the first phase on the upper surface of the islandportion of a third lead; connecting the second transistor and the seconddiode of the first phase to a bonding portion of the second lead by asecond wiring; attaching lower surfaces of the island portion of each ofthe plurality of leads to an upper surface of a circuit board; andencapsulating by a resin the circuit board, the first and secondtransistors, the first and second diodes and the lead frame so that thelead portion of each of the plurality of leads are not covered by theresin.
 13. The method of claim 12, further comprising: mounting a firsttransistor and a first diode of a second phase on an upper surface ofthe island portion of a fourth lead; connecting the first transistor andthe first diode of the second phase to the bonding portion of the firstlead by a third wiring; mounting a second transistor and a second diodeof the second phase on the upper surface of the island portion of thethird lead; and connecting the second transistor and the second diode ofthe second phase to a bonding portion of the fourth lead by a fourthwiring.
 14. The method of claim 13, further comprising: attaching lowersurfaces of the island portion of the fourth lead to the upper surfaceof the circuit board; and encapsulating by the resin the circuit board,the first and second transistors and first and second diodes of each ofthe first and second phases, and the lead frame so that the leadportions of the first, second, third, and fourth leads are not coveredby the resin.
 15. The method of claim 13, further comprising: mounting afirst transistor and a first diode of a third phase on an upper surfaceof the island portion of a fifth lead; connecting the first transistorand the first diode of the third phase to the bonding portion of thefirst lead by a fifth wiring; mounting a second transistor and a seconddiode of the third phase on the upper surface of the island portion ofthe third lead; and connecting the second transistor and the seconddiode of the third phase to a bonding portion of the fifth lead by afourth wiring.
 16. The method of claim 15, further comprising: attachinglower surfaces of the island portion of the fourth and fifth leads tothe upper surface of the circuit board; and encapsulating by the resinthe circuit board, the first and second transistors and first and seconddiodes of each of the first, second, and third phases, and the leadframe so that the lead portions of the first, second, third, fourth, andfifth leads are not covered by the resin.
 17. The method of claim 16,further comprising: mounting an insulative control board on the uppersurface of the circuit board; and mounting a control element on an uppersurface of the insulative control board.
 18. The method of claim 17,further comprising: connecting the control element to the first andsecond transistors of each of the first, second, and third phasesthrough respective wirings.
 19. The method of claim 12, furthercomprising: mounting an insulative control board on the upper surface ofthe circuit board; and mounting a control element on an upper surface ofthe insulative control board.
 20. The method of claim 19, furthercomprising: connecting the control element to the first and secondtransistors of the first phase through respective wirings.